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है”ह”ह

IS 4257-2 (1986): Dimensions for clamping arrangements forporcelain transformer bushings, Part 2: For 72.5 kV and 123kV bushings [ETD 6: Electrical Insulators and Accessories]

IS : 4257 ( Part 2 ) - 1986

Indian Standard DIMENSIONS FOR

CLAMPING ARRANGEMENTS FOR PORCELAIN TRANSFORMER BUSHINGS

PART 2 FOR 72.5 kV AND 123 kV BUSHINGS

Electrical Insulators and Accessories Sectional Committee, ETDC 3

Chairman

SHRI V. D. ANAND

Mem bars

Representing

Central Electricity Authority, New Delhi

DIRECTOR ( TRANS~KISSION ) ( Alternate I to Shri V. D. Anand )

DIRECTOR ( SUB-STATION ) ( Alternate II to Shri V. D. Anand )

SHRI U. R. G. ACHARYA Directorate General of Posts and Telegraphs, Jabalpur

SERI P. P. AQRAWAL ( Alternate ) ADDITIONAL DIRECTOR ( TI ) Research, Designs and Standards Organization

( Ministry of Railways ), Lucknow DEPUTY DIRECTOR ( OHE-II ) ( Alternate )

SHRI R. S. ARORA Directorate General of Supplies and Disposals, New Delhi

SHRI R. P. SEHGAL ( Aiternutc ) SHRI T. D. BANERJEE Orissa State Electricity Board, Bhubaneshwar

SHRI GOURANGA PATRA ( Alternut ) SHRI R. T. CHARI Tag Corporation, Madras

DR P. R. MADHAVAN ( Altcrnutc ) SHRI G. L. DUA Rural Electrification Corporation Ltd, New Delhi

SRRI S. C. KEURANA ( Alternate ) SHRI NA~IN SINOH GREWAL Punjab State Electricity Board, Patiala

SHRI GIAN PRAEASH ( Alternate ) SHRI K. C. JAJU Jaya Shree Insulators, Calcutta

SERI A. K. NA~PAL ( Alternutc ) SHRI I. K. KAPOOR Directorate General of Technical Development,

New Delhi SHRI K. R. KASHYAP High Tension Insulator Factory, Ranchi

SHRI A. K. A~RAWAL ( Alternate )

( Continwd on page 2 )

@ Cepyright 1986

INDIAN STANDARDS INSTITUTION I This publication is protected under the Indian Copyriihf Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act. I

IS : 4257 ( Part 2 ) - 1986

( Continued from page 1 )

Members Representing

SHRI B. KRISHNAMURTHY Bharat Heavy Electricals Ltd, Bhopal SHRI S. P. SINoH ( /,b,UtC 1 )

SEHI J. R. NARLA ( Alternate II ) SHRI SYED KHADER MOHIUDDIN Karnataka State Electricity Board, Bangalore

SHRI R. RAN~ASWAMY ( Alternuts ) SHRI R. V. NADKARNI Maharashtra State Electricity Board, Bombay

SHRI S. P. AMIDWAR ( Alternate ) SHRI P. L. NENE Madhya Pradesh Electricity Board, Jabalpur

SHRI S. Z. HUSSAIN ( Alternote ) SHRI D. S. NELSON Tamil Nadu Electricity Board, Madras

SHRI N. R. SANKARAN ( Alternate ) DR G. M. PEADEE Indian Electrical Manufacturers’ Association, Bombay

SHRI P. RA~ADHANDRAN ( Abxate )

SHRI N. RAMAKRISHNAN W. S. Insulators of India Ltd, Madras SHRI R. G. VANCHEESWARAN ( Alternate)

&tar V. B. Rm MOHAN Central Power Research Institute, Bangalore SHRI K. N. SRINIVASAN ( Alternate )

SHRI K. H. GUBURAJA RAO NGEF Limited, Bangalore SHRI C.S. WARAD ( Alternate)

SHRI S. C. SEN Bengal Potteries Ltd, Calcutta SHRI D. K. MAZUMDAR ( Alternate )

SHRI R. D. SHETH Electra Metal Industries, Bombay SHRI SURENDRA SINQH Government Pottery Development Centre, Khurja

SARI T. B. L. SRIVASTAVA ( Alternate ) SHRI V. B. SIN~H UP State Electricity Board, Lucknow

SHRI S. C. RASTO~I ( Alternate ) SRRI L. VENKATESUBBU Seshasayee Industries Ltd, Vadalur

SHRI R. V. ACRUTHAN ( Alternate ) SHRI U. S. VERMA National Test House, Calcutta

SHRI P. C. PRADHAN ( Alternate ) SHRI S. P. S_4o~uzv, Director General, IS1 ( Ex-ojicio Member )

Director ( Elec tech )

Secretary

SHRI R. K. MONC+A Joint Director ( Elec tech ), IS1

Panel for Dimensions of Bushings, ETDC 3 : P3

Convener

SHRI V. SRINIVASAN W. S. Imulators of India Ltd, Madras

Members

SHRI R. K. A~RAWAL Bharat Heavy Electricals Ltd, Bhopal SHRI M. P. SINC+H ( Alternute I ) SHRI B. KRISHNAXURTHY ( Alternate II )

DIRECTOR ( SUB-STATIONS ) Central Electricity Authority, New Delhi DEPUTY DIRECTOR ( Alternate )

SRRI S. V. MANERIKAR Crompton Greaves Ltd, Bombay SHRI R. G. PRADHAN Bharat Bijlee Ltd, Bombay SHRI P. RAMACHANDRAN TrauS&;mrs & Electricala Kerala Ltd, Angamally

SHRI KURIAKOSE ANTONY ( Alternate ) Sxmr P. S. RAXAN DR U. S. SINOH

NGEF Ltd, Bangalore

SHRI A. D. DUA ( Alternote ) High Tensron Insulator Factory, Ranchi

2

IS : 4257 ( Part 2 ) - 1986

Indian Standard DIMENSIONS FOR

CLAMPING ARRANGEMENTS FOR PORCELAIN TRANSFORMER BUSHINGS

PART 2 FOR 72-5 kV AND 123 kV BUSHINGS

0. FOREWORD

0.1 This Indian Standard ( Part 2 ) was adopted by the Indian Standards Institution on 7 March 1986, after the draft finalized by the Electrical Insulators and Accessories Sectional Committee had been approved by the Electrotechnical Division Council.

0.2 This standard ( Part 2 ) deals with the dimensions of clamping arrangements for 72.5 kV and 123 kV rating bushings to be used with transformers. The materials for the parts have also been specified. The dimensions of clamping arrangements for 12 kV to 36 kV rating bushings are covered in Part 1 of this standard.

0.3 The dimensions of porcelain parts and metal part fittings for transformer bushings for lightly polluted and heavily polluted atmospheres are covered in a series of standards under IS : 3347* and IS : 8603t, respectively.

0.4 In the preparation of this standard, assistance has been derived from DIN 42538 - ‘Transformers, clamping arrangement for bushings’, issued by Deutsches Normenausschuss.

0.5 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test, shall be rounded off in accordance with IS : 2-1960:. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.

*Dimensions for porcelain transformer bushings. tDimensions for porcelain transformer bushings for use in heavily polluted atmos-

pheres. IRules for rounding off numerical values ( revised ).

3

IS : 4257 ( Part 2 ) - 1986

1. SCOPE

1.1 This standard ( Part 2 ) covers the clamping arrangements for porcelain transformer bushings of 72.5 kV and 123 kV ratings.

2. MATERIAL

2.1 The material of various parts shall conform to the relevant Indian Standards as specified below:

Part Material

Clamping member ( see Fig. 1 )

Zinc base alloy 2 according to IS : 713- 1981” or Aluminium alloy 4600 M designation according to IS : 617-19757

Clamping ring ( see Fig. 2 )

Bright round bar according to IS : 9550- 1980:

Nut Bright hexagonal bar, Type 3, Grade 3 ( see Fig. 3 ) A/F 17 of IS : 9550-1980%

Gasket Oil resistant compressed asbestos fibre ( see Fig. 4 ) jointing to Grade BlO according to

IS : 2712-1979s

3. TOLERANCE

3.1 Unless specified otherwise, allowable tolerance on dimensions of any machined part shall be in accordance with medium class of IS : 2102 ( Part 1 )-198011.

3.2 Unless specified otherwise, allowable tolerance of dimensions of any forged or cast part shall be in accordance with the coarse class of IS : 2102 ( Part 1 )-1980/l.

4. SURFACE FINISH

4.1 The surface finish for ferrous Parts shall be hot-dip galvanized according to IS : 4759-19797 or zinc plated according to IS : 1573-1970”” or cadmium plated with chromate passivation Cd 8 Cr according to IS : 1572-196877 subject to agreement between the manufacturer and the purchaser.

*Specification for zinc base alloy ingots for die castings ( second rsvision ). Wpecification for bright bars. SSpecification for aluminium and aluminium alloy ingots and castings for general

engineering purposes ( second revision ). gspecification for compressed asbestos fibre jointing ( second rsvision ). Wpecification for allowable deviations for dimensions without specified tolerances

( first fcuision ) . llspecification for hot dip zinc coatings on structural and other allied products

( firJt fevision ). **Specification for electroplated coatings of zinc or iron and steel (first revision). ttSpecif?cation for electroplated coatings of cadmium or iron and steel (first revision )

4

IS : 4257 ( Part i ) - 1986

4.2 The surface finish for non-ferrous parts shall be electrotinning according to IS : 1359-1977* subject to agreement between the manu- facturer and the purchaser.

5. DIMENSIONS

5.1 The dimensions of components of clamping arrangements shall be in accordance with values given in Fig. 1 to 4.

6. METHOD OF CLAMPING

6.1 The method of clamping of bushings shall be as shown in Fig. 5 and 6. f

*Specification for electroplated coatings of tin ( second revision ).

5

IS : 4257 ( Part 2 ) - 1986

R 690 c -4 All dimensions in millimetres.

FIG. 1 CLAMPING MEMBER

6

IS : 4257 ( Part 2 ) - 1986

BUSHING RATING D mm

72’5 kV/l 250 A 326

123 kV/l 250 A 421

*Thread ends and runout shall be according to IS : 1368-1980 ‘Dimensions of ends of bolts and screws ( second ksion )’ and IS : 1369-1982 ‘Dimensions of screw thread

mn-outs and undercuts ( second revision )’ respectively.

FIG. 2 CLAMPINO RING

7

IS : 4257 ( Part 2 ) i 1986

*Thread runout shall be according to IS : 1369-1982 ‘Dimensions of screw thread run-outs and undercuts ( second revision )’

All dimensions in millimetres.

FIG. 3 NUT

BUSHING RATING

72-5 kV/ 1 250 A 123 kV/l 250 A

4 4 mm 320 365

FIG. 4 GASKET

8

Item .NO.

Particulars NO. of Units par Bushing

1 Clamping Member ( see Fig. 1 ) 8

2 Clamping Ring ( see Fig. 2 ) 1

3 Nut ( SIC Fig. 3 ) 1

4 Gasket ( see Fig. 4 ) 1

5* Stud Ml6x 100, B-8.8, as perIS : 1862-1975t/ 8 Weld Stud Ml6 x 120, St 42-w

6. Hexagonal Nut M16, B-4, IS : 1364 ( Part 2 )-1983f: 8

7* Punched Washer AM16, IS : 2016-19678 8

8 Earthing.$Strip, Size : 85 x 40 x 50 1 Maternal : Electrolytic High-Conductivity Copper as per IS : 191 ( Parts 1 to 10 )-198011

9* Hex, Nut Ml0 S-4, IS : 1364 ( Part 2 )-1983$ 1

*SURFACE FINISH : Galvanized as per IS : 4759-1984 ‘Specification for hot-dip zinc coatings on structural steel and other allied products ( second revision )’ or ELECTROPLATE coating of Cadmium with Chromate Passivation Cd 8 Cr as per IS : 1572-1968 ‘Specification for electroplated coatings of cadmium on iron and steel (Jirst rahion )‘.

?Specification for studs ( second revision ). SSpecification for hexagon head bolts, screws and nuts of product grade A and B: Part 2 Hexagon screws ( size range

M3 to M36 ) ( second reuision ). §Specification for plain washers (first revision ). IlSpecification for copper ( third revision ).

FIG. 5 METHOD OF CLAMPING 72.5 kV/ 1 250 A BUSHING

-

Ite?lZ Particulars No. of Units .NO. fir Bushing

1 Clamping Member ( see Fig. 1 ) 12

2 Clamping Ring ( ~68 Fig. 2 ) 1

3 Nut ( see Fig. 3 ) I 4 Gasket ( see Fig. 4 ) 1

5* Stud Ml6 x 100, B-8.8, as per IS : 1862-1975t/ 12 Weld Stud Ml6 x 120, St 42-w

6” Hexagonal Nut M16, B-4, IS : 1364 ( Part 2 )-1983$ 12

7* Punched Washer AM16, IS : 2016-19675 12

8 Earthing Strip, Size: 0.5 x 40 x 50 1 Material : Electrolytic High-Conductivity Copper as per IS : 191 ( Parts 1 to 10 )-198011

9* Hex, Nut Ml0 S-4, IS : 1364 ( Part 2 )-1983$ 1

*SURFACE FINISH: Galvanized as per IS : 4759-1984 ‘Specification for hot-dip zinc coatings on structural steel and other allied products ( second revision )’ or ELECTROPLATE coating on Cadmium with Chromate Passivation Cd 8 Cr as per IS : 1572-1968 ‘Specification for electroplated coatings of cadmium on iron and steel (Jirsl rauision )‘.

iSpecification for studs ( second revision ) . $Specification for hexagon head bolts, screws and nuts of product grades A and B: Part 2 Hexagon screws ( size

range M3 to M36 ) ( second revision ). $Specification for plain washers (j&l revision ). l/Specification for copper ( third revision ).

FIG. 6 METHOD OF CLAMPING 123 kV/l 250 A BUSHING

_~_ -